<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 300px;
            height: 300px;
            background-color: aqua;
        }
    </style>
</head>
<body>
 <div class="box"></div>
 <script>
    const oBox=document.querySelector(".box");

    function center(e){
        console.log("center");
        console.log(e);
        console.log(this);
    }
    oBox.onmousemove = throttle(center,300);
     
    function throttle(fn,time){
        let lastTime=0;
       return function (e){
        let nowTime=Date.now();
        // 书写一个看门狗
        if(nowTime-lastTime <time){
            return;
        }
        lastTime=nowTime;
        center.call(this,e);
       }
    }
 </script>   
</body>

</html>